(a) Field of the Invention
The present invention relates generally to a freezing conveyor system, and more particularly to a food freezing conveyor system which provides quick freezing and facilitates maintenance and repairs.
(b) Description of the Prior Art
Freezing conveyors are indispensable in frozen food processing. Growing demands for frozen foods result in increasing demands for freezing conveyors. There is a great variety of freezing conveyors which differ according to the kind of food products, processing methods, and quality and nutrition contents of the food products. At present, the most widely used freezing conveyors fall into two types, namely, continuous linear chain conveyors and spiral freezing conveyors.
U.S. Pat. No. 4,378,873 discloses a continuous linear chain conveyor system operating through multiple tiers for transporting a food product which is to be either cooled, frozen or warmed. U.S. Pat. No. 4,584,849 provides an improvement over U.S. Pat. No. 4,078,398 which teaches a freezing airflow apparatus with good airflow and floor space economy. U.S. Pat. No. 4,584,849 aims to provide safe and quiet food freezing tunnels for quick, individual and consistent freezing of food products and for operation over long running times with greater efficiency. The conventional continuous linear chain conveyors or food freezing tunnels are substantially linear in plan structure. Although they have the advantages of simple construction, low costs and volatility, they occupy large floor space. In addition, the operation capacity of continuous linear chain conveyor systems cannot be significantly raised and the energy needed for freezing is easily dissipated.
U.S. Pat. No. 3,938,651 provides a spiral conveyor. A similar invention is found in U.S. Pat. No. 5,105,934 which discloses a conveyor system with an endless conveyor belt employed in a food freezing tunnel. Such a spiral construction has the merits of floor space economy, higher capacity and greater efficiency. But there are several drawbacks which need to be overcome. The internal drum or cage arranged in the middle section of the conveyor uses up a lot of space; the width of the conveyor belt is restricted by the varying speed of rotation of points of varying radii, and the conveying chains may easily wear. Besides, the airflow path is not smooth, i.e., the airflow efficiency not very ideal.